“Use the opportunity to attract potential and efficiency gains from your business.”

Digitisation is progressing steadily, old technologies are being replaced by new ones. This also applies to ISDN. Our interview will tell you what the replacement of ISDN means for companies, where dangers lurk and where opportunities present themselves.


Andrea Meiborg is account and project manager at the STF Group. She advises companies on technical and process-related issues of digital transformation. A focus of Andrea’s work is to support business customers in switching from ISDN to ALL-IP.

Why is ISDN switched off at all? At least as a standard user you have the impression that it works after all.

The replacement of ISDN by ALL-IP has several reasons. ISDN technology is outdated, inefficient and costly for network operators. The increasing digitalization – for example IoT (Internet of Things), M2M (machine to machine communication), software-as-a-service solutions but also the generally increased web usage – requires higher bandwidths. The best way to do this is to bundle applications into a single protocol, the IP protocol.

What companies can expect if they refuse to switch to ALL-IP?

The network operators have partly already started to announce ISDN terminations. If the cancellation time has arrived or ISDN technology is no longer supported, telephony and the Internet will fail. For companies, this can bring the entire business to a standstill, for example if the merchandise management system no longer functions, the ERP system or other SAS products.

Is it then enough to simply switch to a cheap cloud telephone system, and my ISDN problems have vanished into thin air?

In theory yes, in practice no. In companies, the hardware usually has to be adapted, not all telephones are ALL-IP capable, telephone systems only in the rarest cases. Those responsible should pay particular attention to alarm systems, fire alarm and emergency call systems. The communication of these plants and systems usually takes place via ISDN. Other components such as EC cash systems or electric gates could also be affected, as these may communicate via the ISDN interface. Here, it is important to check exactly where ISDN is used everywhere, because a malfunctioning fire alarm system can be extremely dangerous.

It is also important to ensure that the Internet connection used has sufficient capacity for IP telephony. 150kb are required per call in both download and upload. If several employees use Internet applications and others make calls at the same time, this can become critical in some regions with low bandwidth and lead to telephone and Internet failures.

The ISDN replacement therefore poses some challenges for companies, what advantages does it offer?   

Our advice to customers is, if you already have to revise your ICT infrastructure, use the opportunity to lure potentials and efficiency increases out of your business. So check where it makes sense to digitize your processes. Depending on the industry and current status, different measures can lead to this. A customer operating a B2B department store, for example, has used the opportunity to switch from inefficient fax orders to a digital merchandise management system with scanners. It can also be worthwhile to switch to a so-called one-device strategy. This is particularly recommended where the broadband connection is not optimal and ALL-IP therefore does not make sense. However, it is important to note that there is sufficient network coverage (also called in-house supply in buildings) wherever it is used.

How exactly does STF support customers in the replacement of ALL-IP?

For us it is important to support our customers individually, focused on their needs and independent of manufacturers. But of course we have a red thread to follow. We start with a needs analysis in which we work together with the customer to develop scenarios and alternatives that can achieve the minimum and maximum replacement of ISDN. In the minimum case, this is usually an ALL-IP-based telephony as well as ALL-IP-based FAX dispatch and ensuring the functionality of special services such as alarm systems. If the customer wants to use the opportunity to optimize processes at the same time, we work out an extended scenario, for example the use of sensors in production to detect wear and tear of machines at an early stage. In the subsequent as-is analysis, we determine the status quo of the ICT infrastructure. Here we take a close look at what needs to be renewed and which technology can be further used in the future. This is followed by a tailor-made, customer-oriented concept including a cost estimate and timetable for the ISDN replacement.

This might also be of interest to you


Immobilien: Ohne leistungsstarke Vernetzung werden Gebäudewerte sinken


ISDN Interview


Checklist: ISDN replacement: When the company comes to a standstill

Inquiries, comments, criticism:
We always have an ear